Fractional traffic weights don't seem to be set accurately

I have created a stackset called ss-stack with stacks v1 and v2. When I switch traffic using fractional values, the resulting traffic percentage is slightly inaccurate. See the following examples:

zkubectl traffic ss-stack ss-stack-v2 50.1
Name       │Actual│Desired
ss-stack-v1    100      50
ss-stack-v2      0    50.1
Name       │Actual│Desired
ss-stack-v1   50.0    50.0
ss-stack-v2   50.0    50.0

[
  {
    "serviceName": "ss-stack-v1",
    "servicePort": 5678,
    "stackName": "ss-stack-v1",
    "weight": 49.95004995004995
  },
  {
    "serviceName": "ss-stack-v2",
    "servicePort": 5678,
    "stackName": "ss-stack-v2",
    "weight": 50.049950049950056
  }
]

zkubectl traffic ss-stack ss-stack-v2 50.8
Name       │Actual│Desired
ss-stack-v1   50.0      49
ss-stack-v2   50.0    50.8
Name       │Actual│Desired
ss-stack-v1   49.1    49.1
ss-stack-v2   50.9    50.9

[
  {
    "serviceName": "ss-stack-v1",
    "servicePort": 5678,
    "stackName": "ss-stack-v1",
    "weight": 49.09819639278557
  },
  {
    "serviceName": "ss-stack-v2",
    "servicePort": 5678,
    "stackName": "ss-stack-v2",
    "weight": 50.901803607214426
  }
]

The stackset used was:

apiVersion: zalando.org/v1
kind: StackSet
metadata:
  labels:
    application: ss-stack
  name: ss-stack
spec:
  externalIngress:
    backendPort: 5678
  stackTemplate:
    spec:
      replicas: 1
      version: v1
      podTemplate:
        spec:
          containers:
            - name: gw-test-app
              image: hashicorp/http-echo
              args: ["-text", "Stack V1"]
              ports:
                - containerPort: 5678
              resources:
                requests:
                  cpu: 1
                  memory: 100Mi
                limits:
                  memory: 100Mi

It was applied and then reapplied with v1 replaced by v2.

Start by reproducing the fractional traffic changes with the zkubectl traffic commands and the provided StackSet manifest, then trace how the controller calculates and reports weights. Done means requested fractional values produce accurate desired, actual, and StackSet status weights for both examples.